diff --git a/.github/workflows/go.yml b/.github/workflows/go.yml
index a9c4821..32402b1 100644
--- a/.github/workflows/go.yml
+++ b/.github/workflows/go.yml
@@ -18,7 +18,7 @@ jobs:
     - name: Set up Go
       uses: actions/setup-go@v2
       with:
-        go-version: 1.17
+        go-version: 1.18
 
     - name: Build
       run: go build -v ./...
diff --git a/internal/zenutil/color.go b/internal/zenutil/color.go
index d67562b..45e77c2 100644
--- a/internal/zenutil/color.go
+++ b/internal/zenutil/color.go
@@ -27,7 +27,7 @@ func ParseColor(s string) color.Color {
 		}
 	}
 
-	if len(s) >= 10 {
+	if len(s) >= 10 && "rgb" == s[:3] {
 		c := color.NRGBA{A: 0xff}
 		if _, err := fmt.Sscanf(s, "rgb(%d,%d,%d)", &c.R, &c.G, &c.B); err == nil {
 			return c
diff --git a/internal/zenutil/color_test.go b/internal/zenutil/color_test.go
index b252a02..a746aca 100644
--- a/internal/zenutil/color_test.go
+++ b/internal/zenutil/color_test.go
@@ -67,9 +67,26 @@ func TestColor_strings(t *testing.T) {
 		{"#8888", color.NRGBA{0x88, 0x88, 0x88, 0x88}},
 		{"#80808080", color.NRGBA{0x80, 0x80, 0x80, 0x80}},
 		{"rgb(128,128,128)", color.NRGBA{0x80, 0x80, 0x80, 0xff}},
-		{"rgba(128,128,128,0.5)", color.NRGBA{0x80, 0x80, 0x80, 0x80}},
+		{"rgba(128,128,128,0)", color.NRGBA{0x80, 0x80, 0x80, 0x00}},
+		{"rgba(128,128,128,1)", color.NRGBA{0x80, 0x80, 0x80, 0xff}},
+		{"rgba(128,128,128,0.0)", color.NRGBA{0x80, 0x80, 0x80, 0x00}},
 		{"rgba(128,128,128,1.0)", color.NRGBA{0x80, 0x80, 0x80, 0xff}},
 		{"not a color", nil},
+		{"#0", nil},
+		{"#00", nil},
+		{"#000", color.Black},
+		{"#0000", color.Transparent},
+		{"#00000", nil},
+		{"#000000", color.Black},
+		{"#0000000", nil},
+		{"#00000000", color.Transparent},
+		{"#000000000", nil},
+		{"rgb(-1,-1,-1)", nil},
+		{"rgb(256,256,256)", nil},
+		{"rgb(128,128,128,0.5)", nil},
+		{"rgb(127.5,127.5,127.5)", nil},
+		{"rgba(127.5,127.5,127.5,0.5)", nil},
+		{"rgba(128,128,128)", nil},
 	}
 	for _, test := range tests {
 		c := ParseColor(test.data)
@@ -78,3 +95,51 @@ func TestColor_strings(t *testing.T) {
 		}
 	}
 }
+
+func FuzzParseColor(f *testing.F) {
+	f.Add("#000")
+	f.Add("#000f")
+	f.Add("#000000")
+	f.Add("#000000ff")
+	f.Add("#fff")
+	f.Add("#ffff")
+	f.Add("#ffffff")
+	f.Add("#ffffffff")
+	f.Add("#FFF")
+	f.Add("#FFFF")
+	f.Add("#FFFFFF")
+	f.Add("#FFFFFFFF")
+	f.Add("#0")
+	f.Add("#00")
+	f.Add("#000")
+	f.Add("#0000")
+	f.Add("#00000")
+	f.Add("#000000")
+	f.Add("#0000000")
+	f.Add("#00000000")
+	f.Add("#000000000")
+	f.Add("#8888")
+	f.Add("#80808080")
+	f.Add("rgb(-1,-1,-1)")
+	f.Add("rgb(128,128,128)")
+	f.Add("rgb(256,256,256)")
+	f.Add("rgb(128,128,128,0.5)")
+	f.Add("rgb(127.5,127.5,127.5)")
+	f.Add("rgba(128,128,128)")
+	f.Add("rgba(128,128,128,0)")
+	f.Add("rgba(128,128,128,1)")
+	f.Add("rgba(128,128,128,0.0)")
+	f.Add("rgba(128,128,128,0.5)")
+	f.Add("rgba(128,128,128,1.0)")
+	f.Add("rgba(127.5,127.5,127.5,0.5)")
+	f.Add("not a color")
+	f.Add("")
+
+	for _, name := range colornames.Names {
+		f.Add(name)
+	}
+
+	f.Fuzz(func(t *testing.T, s string) {
+		ParseColor(s)
+	})
+}